Cores for precision casting (core materials) used when components such as rotor blades and stator vanes for gas turbines are formed of a ceramic, etc. by a precision casting method. This precision casting method includes a slip casting method, an injection molding method, and so on. The slip casting method molds a core by pouring a slurry in which ceramic powder is mixed into water, etc. into a plaster mold and drying the slurry. The injection molding method prepares a metal mold, heats an injection molding raw material that is in a pellet shape and is formed of a ceramic, or the like using an injection molding machine, and pours the injection molding raw material into the metal mold. This metal mold is cooled, and thereby a core is molded.
The core manufacturing method includes another laminate shaping method. In the laminate shaping method, a laser is applied to material powder such as a ceramic disposed in a layer, and selectively solidifies only a necessary portion from the layer. Afterwards, the layer to which the laser is applied is used as a first layer, and new material powder is disposed on the first layer and is formed as a second layer. A laser is also applied to the second layer and selectively solidifies only a necessary portion, and in the meantime, joins the solidified portion with the portion solidified in the first layer. These steps are repeated, and thereby a core having an intended three-dimensional shape while being laminated layer by layer is formed in the laminate shaping method.
For example, in the description of Patent Literature 1, a ceramic core formed by this laminate shaping method is impregnated with a ceramic reinforcing liquid, and then is sintered. Thereby, the core is manufactured. This core is used to perform injection molding, and thereby a desired casting is manufactured.